Experimental analysis on thermal characteristics of two-phase water in narrow rectangular channels

Highlights: • Experimental investigation on the thermal characteristics of two phase were conducted. • The results indicate that q_ONB is not influenced directly by the system pressure. • It is revealed that bubble detaching diameter is an important factor. The thermal characteristics of two-phase water were experimentally studied under 0.5–5.0 MPa in the 1.0 mm × 50 mm and 2.5 mm × 50 mm narrow rectangular channels. The experimental results about the onset of nucleate boiling (ONB) and the two-phase heat transfer demonstrate the followings. At the onset of nucleate boiling, the wall superheat, inlet subcooling and pressure were discussed. It seemed the inlet subcooling and pressure to have the same effect on ONB. The influence factors of two-phase heat transfer characteristics were investigated in 1.0 mm and 2.5 mm narrow rectangular channels. It is revealed that bubble detaching diameter is an important factor affecting two-phase heat transfer in the narrow rectangular channels.